Sharp MZ-350C Service Manual page 43

M Z 3500
4-12. Read/write from the Z-80 to V-RAM
Read/write of the Model 3500 V-RAM is done via the
UPD7220GDC. There are two methods used to read/write
data. The method (1) is used for the model 3500.
(1) Read/write via the 16 byte FIFO.
(2) Read/write of V-RAM in the DMA mode without
Intervention of the FIFO.
(Outline of the read/wriie data via the FIFO;
NO
YES
Set GDC command code
YES
Set parameter for the command
YES
Set parameter for the command.
Method used to give a command
to the GDC.
Command must be given to the GDC in the same manner.
On next page is the program of the above flowchart.
- 4 8 -